Known hubs for plastic fan wheels are assembled of several parts. In the conventional arrangement, the hub sleeve is a turned part having a periphery onto which a disc is pressed and attached. The plastic fan body is injection molded on this piece. The disc is soldered to the periphery of the steel hub sleeve and engages into the plastic wheel body on the fan wheel so that the torque transmission between the hub sleeve and the wheel body is ensured.
A starter ring is attached concentrically to the hub axis at the end face of the hub. The starter ring can be entrained by a starter device of the engine which can be coupled thereto. The starter device can, for example, be a pull-rope starter having a starter rope. When the starter rope is pulled, entraining elements are brought into meshing engagement with the teeth of the starter ring. When pulling the starter rope, a torque is generated and transmitted from the starter ring via the plastic of the wheel body and the hub sleeve to the crankshaft thereby bringing the engine into operation.
The manufacturing costs of such a hub are very high because, in addition to the material costs of the individual hub components, the manipulative operations when positioning and assembling the hub components are very time intensive when done with the required care.